


A Heart of Goldfish

by 9thdoor



Category: Shingeki no Kyojin | Attack on Titan
Genre: Fluff, M/M, Modern AU, More tags to be added, Slow Build, big time gaps, fish AU
Language: English
Status: In-Progress
Published: 2014-07-08
Updated: 2014-07-08
Packaged: 2018-02-07 23:52:45
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,642
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1918854
Author URL: https://archiveofourown.org/users/9thdoor/pseuds/9thdoor
Summary: <blockquote class="userstuff">
              <p>Eren was finally allowed to get a pet at ten years old based on a few simple terms.<br/>1. He fed it<br/>2. He cleaned where it lived<br/>3. He didn't blame Mikasa for any of the above not being accomplished.<br/>Failing to properly do one of those ended up creating results that surprised him, to say the very least. But he didn't regret it, ever.</p>
            </blockquote>





	A Heart of Goldfish

**Author's Note:**

  * For [notsofriendlyghosts](https://archiveofourown.org/users/notsofriendlyghosts/gifts).



His nose was pressed against the glass, squished and sure to leave a foggy mark that someone would notice and complain about later. Eren wore a grin, however, completely unaware of whatever would happen later, when an already grouchy employee had to wash the fronts of the fish tanks.

In fact, he couldn’t care less about the glass, only what was behind it.

A big-finned, purple, fish. 

Well, he’d started by looking at the small crabs. Then the sea snails. Then he moved over and saw the large, purplish-finned fighting fish that were all kept in individual tanks. 

“Mom!” he cried, backing up and squishing his finger against the glass, looking to his mother who was keeping a good distance from the displays of fish. “This one!”

Carla cast a look to the freckled clerk beside her, who was smiling at Eren’s enthusiastic curiosity. However, he stepped towards Eren, daring to say, “Well, he’s not really a nice type of fish, you know?” The ten-year-old blinked back at him, and the clerk gave further explanation, “He’s a fighting fish, and he does a lot of just sitting around if he’s the only fish in the tank.”

“Then...can’t I just get two?” he asked, sounding accomplished.

Marco, as his name tag said, shook his head. “No, because one would end up hurting the other, and then you’d be stuck with the same situation as before,” he explained, and Eren gave a soft, ‘ohhh,’ frowning. “Hey,” Marco said, pulling the smaller boy’s attention back, “I think I know a fish that you’d like.”

“Really?” Eren asked, looking a bit uncertain, though the worker just kept smiling.

“Really.” Marco promised, turning away from the tank that Eren had been focused on. Instead, he walked a little farther down the wall of tanks, stopping in front of a bright little window, pointing but taking care not to touch the glass. “See?”

The hopeful smile Eren had been wearing fell a little as he looked into the tank. These were just...

“Goldfish?” Eren asked, voice touched with discouragement. His gaze went back to the inside of the tank, and he stared. Though they were just orange—a lot more of that than gold, really—they were sort of... “...shiny,” he mumbled quietly, making Marco smile as he looked back to Carla. 

She nodded encouragingly as Marco turned back to her son, asking him, “Well, what do you think?” Eren seemed a bit conflicted, glancing back to the left where they’d just come from before looking at the goldfish again. One of them, one in particular, seemed much more true to the goldfish name than the others. 

“This one!” he insisted, and this time he wasn’t met with a smile ready to move him to another option, but one that was followed by Marco clasping his hands together. 

Nodding his approval, he said, “That one’s my favorite, actually. Good choice.”

“You won’t miss him, right?” Eren sounded slightly guilty, but Marco just chuckled, shaking his head.

“No, he deserves a better home than a tank like this. He’s pretty, don’t you think?” Eren looked almost as if he suspected that to be a trick question, looking back to the fish in the tank for a few, long moments before directing his gaze back to Marco and giving a nod.

“Good,” the clerk grinned, ruffling Eren’s hair and not letting his smile be dimmed by the disapproving look on the kid’s face. “I’ll grab him for you, just a sec.”

At the thought of having his new and first pet soon, Eren’s grin came right back. “Okay!”

\----------

Eren was incredibly excited the whole car ride home, bouncing the bag with his fish in it on his lap for a few moments before his mother glanced back, calmly chiding him for doing so with the warning that if he wasn’t careful, the fish wouldn’t live past the point when they pulled into the driveway. The thought of losing his new pet so soon—and validating his mother’s worries about getting him a pet in the first place—made Eren immediately go still, staying mostly quiet as he stared into the bag for the remainder of the short ride.

He hopped out of the car eagerly, about to run inside, bag swinging—but he saw the look his mother gave him and stopped before he even started running, pausing mid-stride and sighing before cradling the bag in his arms and walking inside normally.

Even though the water sloshed, this way he wasn’t jerking his poor new pet around, and his fish was kept relatively safe from getting dropped while he had the bag tucked in his arms.

Of course, he had to wait for his mom again once he got to the door, turning his head with an over-exaggerated sigh to see her coming up the walkway to their porch. “Come ooon,” he pleaded, bouncing from foot to foot, forgetting how he’d been so careful not to rock the bag moments earlier.

“I’m coming, I’m coming,” Carla teased with a smile, opening up the door and quickly moving to the side. Eren went past her, bouncing up the stairs and to his bedroom where he’d already placed an almost spherical, clear, glass bowl and filled it up with water and the prettiest rocks (by Eren’s standards) that he could find in the yard. 

“Eren!” his mother called up to the second story, “Remember what Marco said about just letting the bag sit in the bowl before you put him in!”

“Okay!” he yelled back, probably a little bit louder than necessary, but he was excited, and could anyone really blame him? It had taken a lot of convincing (whining and pleading) for his mom to allow him to have a pet of his own at all, let alone one that he kept in his own room. All Carla’s terms had entailed was that Eren be the one with sole responsibility over the fish. He would be in charge of feeding it, cleaning the tank when necessary, and also wasn’t allowed to blame Mikasa for not reminding him if something went wrong.

And Eren had eagerly agreed, not caring about the terms so long as he got his pet. And now he had gotten his fish. 

Eren sat on his bed in his room, the fishbowl on his bedside table and the small, colorful container of fish food beside it. The bag with his goldfish in it bobbed in the water, allowing his new pet to acclimate to the temperature of his new home. 

Fifteen minutes, Marco had said, telling him that if he didn’t take that time to let the fish adjust and put him straight in the water the shock of change could end up killing him. So Eren swung his legs back and forth as he sat on the edge of the bed, ticking off the seconds in his mind.

As almost everyone knew, that only made the time pass more slowly, and Eren was grateful when Mikasa appeared in the doorway of his room. “What kind of fish did you decide to get?” she asked, taking a few steps towards him. Mikasa had moved in with them a little more than a year ago now, and she and Eren got along well most of the time, aside from the normal amount of quarrels that occurred between almost all siblings. 

“Just a normal goldfish,” Eren said, shifting to face the bowl better as she came over, staring through the glass and plastic to look at his fish. “The guy at the store said that if I got the really cool looking one, he’d just sit around and do nothing, and if I bought two of those, they’d kill each other.”

“Then it’s a good thing you didn’t get that kind,” Mikasa said simply, kneeling beside the nightstand to look at the fish as well. 

“But isn’t this one pretty?” Eren said, shifting to be on the floor beside her and sounding excited, giving her an expectant look, though she was focused on watching the goldfish make small circles in the bag. 

Mikasa nodded, looking to Eren with a frown and saying, “When’re you going to let him out?” That was an excellent question, he thought, looking away from her to the clock. Perfect!

“Now!” he exclaimed happily. Eren sprung up to his feet, grabbing the top of the bag and un-bunching the rubber-band from around the looser top, then tilting the bag, letting the water start to leak out, filling the bowl higher and finally spilling the goldfish into the bowl. The two of them watched the fish swim around in circles for a few moments, adjusting to its new environment before Mikasa stood up.

“What’re you going to name him, Eren?” she asked, turning her gaze from the fish to her brother, seeing his brow furrow in concentration. His first instinct was too obvious, he thought, much too predictable and childish. But what else would he call it? Eren didn’t want to decide then, with Mikasa watching, and so he shrugged. But he definitely wouldn’t name him Goldie.

“I dunno yet, I’ll decide by tomorrow.”

“You have to tell me, I don't want to just call him the fish," Eren nodded. "Dinner will probably be ready soon,” she said, turning to head out of his rather cramped room, littered with the occasional dirty shirt or pair of pants. Eren didn’t respond, kneeling at his bedside again to watch the slight flash of the goldfish’s fins as he swam around the small tank, sunshine still filtering through the blinds and keeping his room bright.

\----------

“Don’t stay up messing around, okay Eren?” Carla said, pressing a kiss to her son’s forehead and pulling the covers up nearly to his chin, making him frown. 

He almost immediately squirmed, scooting them down further so that he had his arms out on his chest. He gave a reluctant, “Yeah, alright mom.” She smiled despite his huffy attitude, turning away from him to switch on a generic-looking night-light that Eren would deny needing to anyone else. 

“Goodnight Eren,” she said, turning off the light to the room and shutting the door behind her as she went into the hallway, going to the next room to check on Mikasa and tell her to sleep as well. Eren yawned and rolled onto his side so that he was facing the fishbowl, able to see his goldfish swimming around. Thinking about what its name would be, he closed his eyes, drifting off to sleep relatively quickly. 

\----------

Eren didn’t expect to wake up in the middle of the night, but when he did, he’d completely changed positions. He had a habit of doing that in his sleep, completely moving around and tangling himself in his sheets during the night.

Now he was on his back, staring straight up at the ceiling. Rather than being entangled in his bed spread, tonight he was almost completely uncovered and a little cold despite wearing his fleecy pajamas with robots. Of course, when waking up like that, most people would assume they had just kicked off their comforter and sheets, and for a moment Eren did, sitting up in a move to pull the comforter back towards himself.

But when he blinked more, needing to be able to actually see so that he could grab the covers and get his blanket back properly, Eren thought he was dreaming. 

Because there, sitting at the very edge of the bed and presumably in danger of falling off, was a blond boy with Eren’s boring blue and green plaid comforter pulled up over his chest. On any other occasion he would’ve screamed, probably, but right now he just gaped. The hand that he had made a move to bring forward dropped right back to his side as the two stared at each other. It was obvious that the boy hadn’t counted on the person who he was stealing covers from waking up.

There was a good ten seconds of silence between them before Eren said what came to mind first, not ask who this was but — 

“Give my covers back!” he whispered, though he didn’t bring his hands up from where they were fisted on either side of him, clutching the sheets covering the mattress. Eren’s voice was surprisingly quiet given the shock shown by his wide eyes, but at the moment the only thing he could think of was how mad his mom would be if she was woken up in the middle of the night to him yelling. 

“But—it’s cold!” the smaller boy (or at least, Eren assumed he was smaller from the image of him wrapped up in a big fluffy comforter) exclaimed, causing Eren to whip a single finger over his own lips with a hiss of, “Shhh!” 

The blond shut his mouth immediately, looking behind him to where the door of Eren’s bedroom was as if worried that there was something happening that made him need to be quiet. 

“My mom will kill us if she wakes up,” Eren explained quietly, hugging himself, still missing his covers. The other merely nodded, not saying anything. Eren was staring at him, fascinated and, of course, confused. When the gaze of the boy opposite him shifted to the fishbowl lit dimly by his room’s single nightlight, Eren followed the motion, looking at the bowl.

Empty.

“Sunshine’s gone!”

Eren had broken his own rule just then, speaking at an almost-above-normal volume as his gaze swung back to the boy at the end of his bed who had just mimicked Eren’s action of shushing him, finger to his mouth. 

“You didn’t feed me!” the blond insisted, as if that was reasoning for Eren’s fish missing. As if that mattered now, as if this stranger getting fed had anything to do with —

“What?!” Eren said, definitely above the normal level of speaking aloud now, springing forward and sitting on his knees, looking at the other incredulously. “You don’t mean that you—what the hell?”

Swearing was a bad thing to do, according to his mother and just about any adult who heard a bad word come out of his mouth, but if any of the people who had criticized him were in his situation now, Eren was almost positive they’d swear too.

“Be quiet!” the boy whisper-yelled, as only small children seemed to have the ability to do, managing to convey their urgency while still avoiding getting in trouble. Eren didn’t want to do what Sunshine was saying (he decided on calling him that for now, since he’d wanted that to be his name anyways), though he didn’t see much of a choice, as getting in trouble with mom would probably end up with her taking his new pet away, and that was the last thing he wanted. 

“Sorry Sunshine,” Eren apologized, and the blond at the end of his bed tilted his head to the side.

“For not feeding me, or for being too loud?” Sunshine scooted on the bed, pulling the comforter more tightly around him and looking at Eren inquisitively. 

Eren apologizing was something that, as long as anyone remembered, had been few and far between. And so when he did say sorry for doing something like chasing the neighbors' dog for half a mile to try and get the newspaper (ending up soaked to the bone and muddy, much like the dog), no one questioned it for authenticity or causation. 

“For both, I guess,” he answered, voice carefully quiet a moment later.

“And also,” the boy said, taking a rather matter-of-fact tone, “My name isn’t Sunshine, it’s Armin.” Eren scrunched up his nose, leaning back a little in an obvious mix of confusion and distaste.

“That doesn’t make any sense,” he said, sounding slightly incredulous as he went on, “You’re not even supposed to have arms! You’re a fish!”

“I—“ Armin started, expression revealing that he was more than a little taken aback by Eren’s exclamation, though he soon realized that it wasn’t a joke. “I don’t think that’s really how it works.” Sighing, the frustrated brunet reached out again for the covers, this time grabbing those even though Armin was still gripping them for warmth.

“At least let me have the blankets back Sunshine.”

“It-it’s still cold! And I’m Armin, not Sunshine, I just told you that, Eren.” 

Eren’s mouth opened again in surprise, and his startled reaction was obviously not lost on Armin. “How’d you know my name?” he immediately asked, not loosening his grip on the comforter in the slightest. 

“Your—that girl called you that, didn’t she? So I figured that was your name.” Armin shrugged, tilting his head slightly in near-confusion. He wasn’t aware he’d done something that should’ve taken Eren by surprise at all. “Is she your sister?”

His mouth was still open, but he pulled it shut after realizing how silly he must’ve looked. Eren nodded, “Yeah, that’s Mikasa.” Armin nodded, glad to have gotten an answer and not having scared or angered Eren to the point of making it so that he was unwilling to respond to simple questions.

“So,” Eren said, clearly still a little uncertain about the whole situation, “You’re...you’re a fish? And a person?” The entire, limited understanding he had of Armin’s situation could be summed up in those few words. But the blond nodded enthusiastically, happy that Eren wasn’t going to accuse him of being a robber or something like that.

“Yes,” Armin answered, “And I’m hungry.”

Right, Eren had almost forgotten about that. The container of fish flakes still sat on his bedside table, unopened. “Sorry,” he muttered, not looking straight up at Armin. There was something about the other that seemed so completely sincere, to the point that he knew lying would be very hard, maybe even pointless. And doing something like forgetting to feed him on the very first day, something that he’d agreed to taking responsibility for, tainted his own trustworthiness greatly. 

“It’s okay,” the blond said softly, seeing that Eren was clearly ashamed of what he’d done (or forgotten to do), and apologetic at the very least. “Can you feed me soon though?” Almost as soon as he’d asked the question, there was a soft gurgle from inside his temporary nest of a blanket, and he looked embarrassed. “Maybe once I’m back in the bowl, if that’s okay.”

Now Eren grinned at the growl of Armin's stomach, nodding a, “Sure.” However, no matter how happy he was to have a somewhat-unconditional new friend, he was still tired, given that if he'd looked at the clock he would have realized that it was just a little past two in the morning. “But, uh, when you go back in, you know that you talking and stuff is going to have to be a secret, right?” The thought of having Armin, his first pet being able to talk and spend time with him was terribly exciting, but a part of him really expected to wake up the next morning with a normal goldfish. And there was no way he could tell anyone about this, if it was real. 

Armin’s face fell a little, but then he smiled, “Yeah, I’m a secret.”

“And I’ll call you Sunshine for everyone else,” Eren decided, looking a little distasteful again, “Because Armin’s a weird name.”

“It’s not that weird!” the blond protested, still up to his shoulders in Eren’s blanket. The other boy stuck out his tongue, to which Armin sighed. Eren yawned a moment later, and Armin followed suit. They really were contagious, especially if you were looking right at someone who had just yawned. 

“I—I think I should probably go back in there now,” Armin said, more quietly than they’d been speaking together, looking to the bowl, “And then you can feed me.”

“But I wanna talk more!” Eren was frowning and Armin was sighing, already able to tell that Eren was a little stubborn. “Besides, I’m not even tired.”

Okay, maybe more than a little. 

“Well I am,” Armin retorted, picking himself up to stand, legs wobbly as he took a couple shaky steps to be beside the fishbowl. It was impressive that he managed that, really, given that he didn't exactly have a lot of experience on two legs.

Eyebrows pushing together in mild befuddlement, Eren asked, “What’re you doing?”

“Getting back in.” Armin made the answer seem obvious, staring at the bowl. “I’ll talk to you tomorrow, I guess.” He smiled, and Eren nodded, still a bit disbelieving and sleepy. 

“Okay,” he said dumbly, nodding again. He had no idea how Armin planned to get back in the bowl, but with him standing right beside it like that, it almost seemed that he planned to jump right in. Eren reached up to rub his eyes in an attempt not to fall asleep right there, and by the time he’d opened them again, his comforter was in a pile on the floor. Looking quickly to the bowl, he saw his goldfish, making a slow circle. Before allowing himself to lie down and sleep, Eren grabbed the fish food container, sprinkling a few flakes into the bowl and seeing Sunshine set to work on it. 

With a sigh, he laid down to watch, forgetting his cold for the moment, and before he knew it Eren was fast asleep.

The next morning Eren woke up, curled into a ball and shivering, but nearly shot straight up as soon as he remembered, and was in a hurry to check everything. Sure enough, the blanket was still on the floor just in front of his nightstand, and when he looked, there was Sunshine, as he’d call him, swimming between the artificial plastic leaves of the fake plant Eren had decided to stick in the tank.

Not a dream.

**Author's Note:**

> Wow, yeah. I did it. I did the fish!AU. I'm sorry, I kind of have no idea what I'm doing. This started out as a very simple birthday fic for notsofriendlyghosts, and is going to end up multi-chapter, spread over a few years.  
> Honestly. Goldfish!Armin. What am I doing?  
> Unbeta'ed, let me know if there are any glaring mistakes.


End file.
